feat: enhance BaseVectorStorage for model isolation

Why this change is needed:
To enforce consistent naming and migration strategy across all vector storages.

How it solves it:
- Added _generate_collection_suffix() helper
- Added _get_legacy_collection_name() and _get_new_collection_name() interfaces

Impact:
Prepares storage implementations for multi-model support.

Testing:
Added tests/test_base_storage_integrity.py passing.

lightrag/base.py

@@ -220,6 +220,25 @@ class BaseVectorStorage(StorageNameSpace, ABC):
     cosine_better_than_threshold: float = field(default=0.2)
     meta_fields: set[str] = field(default_factory=set)
 
+    def _generate_collection_suffix(self) -> str:
+        """Generates collection/table suffix from embedding_func.
+
+        Returns:
+            str: Suffix string, e.g. "text_embedding_3_large_3072d"
+        """
+        return self.embedding_func.get_model_identifier()
+
+    def _get_legacy_collection_name(self) -> str:
+        """Get legacy collection/table name (without suffix).
+
+        Used for data migration detection.
+        """
+        raise NotImplementedError("Subclasses must implement this method")
+
+    def _get_new_collection_name(self) -> str:
+        """Get new collection/table name (with suffix)."""
+        raise NotImplementedError("Subclasses must implement this method")
+
     @abstractmethod
     async def query(
         self, query: str, top_k: int, query_embedding: list[float] = None

tests/test_base_storage_integrity.py

@@ -0,0 +1,34 @@
+import pytest
+from lightrag.base import BaseVectorStorage
+from lightrag.utils import EmbeddingFunc
+
+def test_base_vector_storage_integrity():
+    # Just checking if we can import and inspect the class
+    assert hasattr(BaseVectorStorage, '_generate_collection_suffix')
+    assert hasattr(BaseVectorStorage, '_get_legacy_collection_name')
+    assert hasattr(BaseVectorStorage, '_get_new_collection_name')
+
+    # Verify methods raise NotImplementedError
+    class ConcreteStorage(BaseVectorStorage):
+        async def query(self, *args, **kwargs): pass
+        async def upsert(self, *args, **kwargs): pass
+        async def delete_entity(self, *args, **kwargs): pass
+        async def delete_entity_relation(self, *args, **kwargs): pass
+        async def get_by_id(self, *args, **kwargs): pass
+        async def get_by_ids(self, *args, **kwargs): pass
+        async def delete(self, *args, **kwargs): pass
+        async def get_vectors_by_ids(self, *args, **kwargs): pass
+        async def index_done_callback(self): pass
+        async def drop(self): pass
+
+    func = EmbeddingFunc(embedding_dim=128, func=lambda x: x)
+    storage = ConcreteStorage(namespace="test", workspace="test", global_config={}, embedding_func=func)
+    
+    assert storage._generate_collection_suffix() == "unknown_128d"
+    
+    with pytest.raises(NotImplementedError):
+        storage._get_legacy_collection_name()
+        
+    with pytest.raises(NotImplementedError):
+        storage._get_new_collection_name()
+